big zap off K4900 chassis; bad fly?

mc300baud

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feeling confident after repairing the bad yoke on my K7000 9" tonight, i hooked up a K4900 chassis that had been sold cheap to me as untested but complete. the picture came up but it was dim so i reached back to turn up the SCREEN and zap! i took a nice hit off the chassis frame next to the flyback. even got a little burn spot on my pinky (first time i can remember that happening from an electrical shock.)

from what i remember on a K4900 (and all chassis?) this usually means the fly is going bad. does my memory serve me well or should i be looking at some other cause?
 
Is the ground wire for the picture tube hooked up? Also - although I've done it a couple times, its not the greatest idea to adjust the flyback with your bare hands.
 
tube ground was hooked up, nothing looks amiss, chassis is clean and no noticeable damage to the flyback (i know this doesn't mean it isn't bad...)
 
tube ground was hooked up, nothing looks amiss, chassis is clean and no noticeable damage to the flyback (i know this doesn't mean it isn't bad...)

How close were your hands to the transistor cans on the side?

I've taken a hit off of them (got too close to the top of the cap on them) and it lit me up pretty good, nice electrical burn and everything.
 
Damn ! I hate adjusting the monitor when its on . I was just adjusting a 4900 and it scared the crap out of me having to mess around back there . I wanna get some type of tool or something .
 
How close were your hands to the transistor cans on the side?

I've taken a hit off of them (got too close to the top of the cap on them) and it lit me up pretty good, nice electrical burn and everything.

OOOH I forgot about those. I was working on a monitor once and actually full out put my finger on the HOT while the monitor was one. Sparks were jumping from my finger to the heat sink. Actually twitched a bit after that. Prob the worst shock I ever got. We measure 7kv between the can and the heat sink! (maybe not much current but the voltage was def there!)
 
OOOH I forgot about those. I was working on a monitor once and actually full out put my finger on the HOT while the monitor was one. Sparks were jumping from my finger to the heat sink. Actually twitched a bit after that. Prob the worst shock I ever got. We measure 7kv between the can and the heat sink! (maybe not much current but the voltage was def there!)

I had a pinhole in the top of a K6100 flyback shoot voltage (about 25,000 volts) out the top while I was adjusting the HV pot. Just as I was getting the B+ to the proper setting, it jumped right to my hand (I was using a plastic screwdriver). I let out quite a yell and my wife came running to find me holding my hand, heart racing, and breathing a little rapidly. Had a cut on my hand (either from the bolt of electricity or from it jerking into something), and it took me 30 minutes to figure out what happened to the screwdriver (went flying across the room)...
 
Turn off the lights and look for any electricity hitting the frame. Check to make sure no parts underneath are touching the frame...
 
no sparks, nothing touching the frame. would there be some way to test the stray voltage on the chassis ground or frame? i'm not wishing to repeat the experience from last night if i can help it.
 
so nobody can answer my initial question?

which was, is a large voltage drop to ground/chassis indicative of a going-bad flyback in a K4900? like, ow! ow! painful large.

i remember hearing this at least once if not several times over the years.
 
Maybe. How's that for an answer?

Perhaps you have a spark jumping from the flyback to the frame, so you get shocked.

Or maybe there is a problem with the dag connection, so there is no place for the "discharge voltage" to go except the frame. A 25k7000 with no dag connection will short voltage to the frame, causing a nasty shock and sometimes chassis damage.

Or maybe a wire popped off a HOT or something and is touching the frame.

Or the anode wire has a cut and is sparking.

Or there's a short in the degauss coil that is electrifying the frame.

Or the neck has a crack and voltage is leaking out.

Or....
 
thanks! that gives me a number of other places to look before changing out the flyback (i picked up a broken chassis with for parts the other day; hopefully that flyback is good.)
 
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